The invention relates to a method for mounting, on a motor vehicle, at least one transverse underbody structure element and a technical front panel which is intended to be mounted at a longitudinal end of a body shell structure element of the vehicle.
The invention relates more specifically to a method for mounting, on a motor vehicle, at least one transverse underbody structure element and a technical front panel which is intended to be mounted at a longitudinal end of a body shell structure element comprising two transversely opposed rails and two transversely opposed parts of the body shell structure element.
Numerous examples of mounting methods of this type are known.
It is known practice using such a method to mount a vehicle underbody structure element upward in a vertical direction.
For example, it is known practice to mount a cross member upward in the vertical direction under elements or teardrop mounts which hang down vertically from the rails of the vehicle.
It is possible at the same time to mount a technical front panel that rests on the underbody structure element of the vehicle.
Hence, document FR-A-2 838 094 discloses how to mount vertically upward the assembly that consists of the cross member and of the technical front panel resting on said cross member.
In some cases, the transverse size of the technical front panel makes it impossible to mount directly in the vertical direction. This is the case, for example, when the transverse size of the technical front panel exceeds the transverse size of teardrop mounts.
In such circumstances, it is known practice for the technical front panel to be positioned on the cross member that forms the underbody structure element, to then tilt it forward slightly and then attach the cross member under the teardrop mounts, the technical front panel then slipping in front of the teardrop mounts, before finally angling the technical front face back against the longitudinal end of the body shell structure element before attaching it thereto.
In such circumstances, the final position of the technical front panel is determined by its prior positioning on the underbody structure element.
Now, in most present-day vehicles, the technical front panel also carries a fair number of points of attachment for vehicle bodywork elements, particularly attachment points for a vehicle front bumper or fender.
The final positioning of these attachment points is of key importance to the final aesthetic look of the vehicle. Specifically, the bumper or fender has to be fitted very accurately with respect to the vehicle body shell structure element which is intended to carry bodywork elements such as the hood, the wings or the headlamps, with which the bumper or fender has to be a perfect fit.
Now, the positional clearances for the underbody structure element are very imprecise, because the teardrop mounts to which this element is attached have themselves been fitted with excessive clearances with respect to the body shell structure element of the vehicle, and also using a different frame of reference.
It would therefore be desirable to be able to position the technical front panel directly with respect to the bodyshell structure element of the vehicle in order to guarantee minimal positioning tolerances, while at the same time keeping to the mounting method described hereinabove, performed upward in a vertical direction, which is particularly well suited to mass assembly on a production line.